A control method and device for a laser ultrasonic system

Abstract

The present invention relates to the field of ultrasonic technology, and in particular to a control method and device for a laser ultrasonic system, wherein the laser ultrasonic system includes a laser and an ultrasonic holographic lens; the ultrasonic holographic lens can reconstruct a holographic sound field of one or more preset frequencies, and is suitable for obtaining a holographic sound field at one or more preset frequencies by pulse or continuous modulation of a laser beam. Specifically, a previously preset laser beam is obtained, and a light spot is generated after optical focusing; the light energy of the light spot is absorbed to generate ultrasonic waves, and the ultrasonic waves are acoustically constrained to form a laser ultrasonic field; the laser ultrasonic field is acoustically matched and coupled to an acoustic holographic layer to generate a holographic sound field in the medium. The present invention only needs to control the excitation laser, and can realize single or multiple focused ultrasonic sound fields of one or more preset frequencies in various propagation media in a time-sharing or simultaneous manner through an ultrasonic holographic lens, and has better degrees of freedom.

Description

Technical Field

[0001] The present invention relates to the field of ultrasonic technology, and in particular to a method and device for controlling a laser ultrasonic system. Background Art

[0002] Acoustic holography technology has become an important part of a wide range of acoustic applications, such as biomedical imaging, medical treatment, and acoustic tweezers. The basis of holography technology is the spatial storage of the phase and amplitude profiles of the desired wavefront, so that when illuminated with a suitable coherent source, the wavefront is interferometrically reconstructed to target the acoustic field. Modern computer-generated holograms skip the process of recording the hologram from a physical scene and instead calculate the required phase profile before rendering it for reconstruction.

[0003] In the prior art, traditional phased systems require the configuration of array ultrasonic sensors. Therefore, the existing phased systems have problems of high manufacturing difficulty and high cost. Based on this phased system, the traditional control method limits the number of channels for controlling the laser ultrasonic field, making it difficult to obtain holographic sound fields at multiple frequencies and lacking the freedom of controlling the phased system. Summary of the Invention

[0004] The present invention aims to at least improve one of the technical problems existing in the prior art. For this purpose, the present invention proposes a method and device for controlling a laser ultrasonic system.

[0005] The technical solution of the present invention is as follows:

[0006] A method for controlling a laser ultrasonic system, wherein the laser ultrasonic system includes:

[0007] A laser for emitting a laser beam;

[0008] An ultrasonic holographic lens, which includes an optical focusing layer, an acoustic confinement layer, an optical absorption layer, an acoustic matching layer, and an acoustic holographic layer arranged in sequence along the laser optical path direction. The optical absorption layer is used to absorb the optical energy of the laser beam to generate ultrasonic waves; the acoustic holographic layer includes a plurality of holographic units with different thicknesses, and the phase and amplitude of the ultrasonic waves are controlled by adjusting the thickness of the holographic units to meet the reconstruction of holographic sound fields at multiple preset frequencies;

[0009] The control method is applicable to continuously modulating a laser beam to obtain holographic sound fields at its multiple preset frequencies, and includes:

[0010] S1, obtaining a continuously modulated laser beam at a previous preset frequency, and generating a light spot after optical focusing by the optical focusing layer;

[0011] S2, the optical absorption layer absorbs the optical energy of the light spot to generate at least one ultrasonic wave, and the acoustic confinement layer acoustically confines the ultrasonic wave to form a laser ultrasonic field;

[0012] S3. Use the acoustic matching layer to acoustically match and couple the laser ultrasonic field to the acoustic holographic layer, generating a holographic sound field at a preset frequency in advance in the propagation medium;

[0013] Repeat S1 to S3 to sequentially complete obtaining the holographic sound field at its subsequent preset frequency by continuously modulating the laser beam.

[0014] A control method for a laser ultrasonic system, wherein the laser ultrasonic system includes:

[0015] A laser for emitting a laser beam;

[0016] An ultrasonic holographic lens, which includes an optical focusing layer, an acoustic confinement layer, an optical absorption layer, an acoustic matching layer, and an acoustic holographic layer arranged in sequence along the laser optical path direction. The optical absorption layer is used to absorb the optical energy of the laser beam to generate ultrasonic waves; the acoustic holographic layer includes a plurality of holographic units with different thicknesses, and the phase and amplitude of the ultrasonic waves are controlled by adjusting the thickness of the holographic units to meet the requirement of reconstructing the holographic sound field at the target preset frequency;

[0017] The control method is applicable to obtaining the holographic sound field of a pulsed laser beam at its target preset frequency, and includes:

[0018] Obtain a pulsed modulated laser beam, which generates a light spot after being optically focused by the optical focusing layer;

[0019] The optical absorption layer absorbs the optical energy of the light spot to generate at least one ultrasonic wave, and the acoustic confinement layer acoustically confines the ultrasonic wave to form a laser ultrasonic field;

[0020] Use the acoustic matching layer to acoustically match and couple the laser ultrasonic field to the acoustic holographic layer, generating a holographic sound field at the target preset frequency in the propagation medium.

[0021] In a possible technical solution, further, when the optical absorption layer generates ultrasonic waves,

[0022] If the number of ultrasonic waves is greater than one, the multiple ultrasonic waves will superimpose on each other to form an ultrasonic plane wave, and the frequency of the ultrasonic plane wave is consistent with the preset frequency of the acoustic holographic layer;

[0023] Acoustically confine the ultrasonic plane wave to form a laser ultrasonic field.

[0024] In a possible technical solution, further, the optical focusing layer includes an optical focusing lens, and the optical focusing lens is one or more hemispherical lenses for condensing the laser beam to generate at least one ultrasonic wave.

[0025] In a possible technical solution, further, the phase of the ultrasonic wave and the thickness of the holographic unit satisfy the following relationship:

[0026] ,

[0027] in, represents the phase of the ultrasonic wave, Indicates the preset ultrasonic frequency, is the speed of sound in the propagation medium, represents the speed of sound of the holographic unit, Indicates the thickness of the holographic unit.

[0028] In a possible technical solution, further, the amplitude of the ultrasonic wave and the thickness of the holographic unit satisfy the following relationship:

[0029] ,

[0030] in, represents the amplitude of ultrasonic wave, It represents the sound pressure of the ultrasonic spherical wave emitted by the acoustic matching layer after the acoustic characteristics are matched. represents the thickness of the holographic unit, represents the acoustic impedance of the acoustic matching layer, represents the impedance of the acoustic holographic layer, represents the acoustic impedance of the propagation medium, Represents the wave number of the acoustic holographic layer.

[0031] According to the control method of the laser ultrasonic system of the embodiment of the present invention, there is no need to configure an array ultrasonic sensor. Only by controlling the preset excitation laser, multiple focused ultrasonic sound fields of single or multiple preset frequencies can be realized in various propagation media in a time-sharing or simultaneous manner through the ultrasonic holographic lens. Compared with the existing control method with only one center frequency, the ultrasonic focusing focal position and power in the control method of the present invention can be adjusted, and have better freedom.

[0032] According to the control method of the laser ultrasonic system of the embodiment of the present invention, long-distance non-contact laser driving can be achieved by using a laser without the need for high-voltage excitation of cables and wired connections. Compared with the traditional ultrasonic field control method that relies on ultrasonic sensors, the durability, safety, convenience and applicability of use are greatly improved.

[0033] A control device for a laser ultrasonic system, wherein the device is used to execute the control method for the laser ultrasonic system as described above, comprising:

[0034] A laser ultrasonic system, comprising a laser and an ultrasonic holographic lens, for obtaining a holographic sound field by transmitting a laser beam emitted by the laser through the ultrasonic holographic lens;

[0035] An identification module, configured to identify a holographic sound field and feedback holographic sound field information, and is disposed on the identification surface of the holographic sound field;

[0036] A control module, respectively connected to the identification module and the laser, is configured to control the laser to emit a new laser beam after obtaining the holographic sound field information, for the ultrasonic holographic lens to reconstruct a new holographic sound field.

[0037] In a possible technical solution, further, the ultrasonic holographic lens includes:

[0038] An optical focusing layer, configured to obtain a previously preset laser beam and generate a light spot after optical focusing;

[0039] An acoustic constraint layer, configured to allow the forward penetration of the laser beam;

[0040] An optical absorption layer, configured to absorb the light energy of the light spot and generate at least one ultrasonic wave. The ultrasonic wave performs acoustic constraint and reflects and superimposes on the acoustic constraint layer to form a laser ultrasonic field;

[0041] An acoustic matching layer, configured to perform feature matching processing on the laser ultrasonic field;

[0042] An acoustic holographic layer, configured to perform holographic processing on the laser ultrasonic field and generate a holographic sound field in the propagation medium.

[0043] A laser ultrasonic medical device, including a regulating device of the above-mentioned laser ultrasonic system. Among them, the laser ultrasonic medical device can be used for ultrasonic manipulation and driving, ultrasonic detection imaging, low-power ultrasonic stimulation, power ultrasonic treatment, etc.

[0044] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be understood through the practice of the present invention. Description of the Drawings

[0045] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0046] Figure 1 is a schematic diagram of a regulating device of a laser ultrasonic system according to Embodiment 1 of the present invention;

[0047] Figure 2 is a schematic diagram of the structure of a frequency-mixed ultrasonic holographic lens according to Embodiment 1 of the present invention;

[0048] Figure 3Schematic flowchart of the regulation method of the laser ultrasonic system according to Embodiment 1 of the present invention;

[0049] Figure 4 Schematic diagram of generating a focused sound field with a preset frequency of 200 kHz in air according to Embodiment 1 of the present invention;

[0050] Figure 5 Schematic diagram of generating a focused sound field with a preset frequency of 500 kHz in air according to Embodiment 1 of the present invention;

[0051] Figure 6 Schematic diagram of the structure of the single - frequency ultrasonic holographic lens according to Embodiment 2 of the present invention;

[0052] Figure 7 Schematic diagram of generating a focused sound field with a preset frequency of 5 MHz in water according to Embodiment 2 of the present invention.

[0053] Reference numerals:

[0054] Laser ultrasonic system 100

[0055] Laser 1, ultrasonic holographic lens 2;

[0056] Optical focusing layer 11, acoustic confinement layer 12, optical absorption layer 13, acoustic matching layer 14, mixed - frequency acoustic holographic layer 15, single - frequency acoustic holographic layer 16;

[0057] Holographic unit 150. Detailed implementation manners

[0058] The embodiments of the present invention will be described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0059] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there may also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time.

[0060] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs. The terms used in the description of the present invention in this specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0061] In the description, claims and drawings of this application, the terms "first", "second", "third", etc. are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a series of steps or units are included, or optionally, steps or units not listed are also included, or optionally, other steps or units inherent to these processes, methods, products or devices are also included.

[0062] Only parts relevant to this application are shown in the drawings, rather than all the content. Before discussing the exemplary embodiments in more detail, it should be mentioned that some exemplary embodiments are described as processes or methods depicted as flowcharts. Although the flowcharts describe the operations (or steps) as sequential processes, many of the operations can be performed in parallel, concurrently or simultaneously. In addition, the order of the operations can be rearranged. The process can be terminated when its operations are completed, but there can also be additional steps not included in the drawings. The process can correspond to a method, function, procedure, subroutine, subprogram, etc.

[0063] The terms "component", "module", "system", "unit", etc. used in this specification are used to represent computer-related entities, hardware, firmware, combinations of hardware and software, software, or software in execution. For example, a unit can be, but is not limited to, a process running on a processor, a processor, an object, an executable file, an execution thread, a program, and / or distributed between two or more computers. In addition, these units can be executed from various computer-readable media on which various data structures are stored. A unit can communicate, for example, through signals with other systems via local and / or remote processes according to signals having one or more data packets (such as data from a second unit interacting with a local system, a distributed system, and / or a network. For example, the Internet interacting with other systems through signals).

[0064] Embodiment 1

[0065] Refer to Figure 1 and Figure 2 As shown, this embodiment provides a control device for a laser ultrasonic system, wherein the control device includes:

[0066] The laser ultrasonic system 100 includes a laser 1 and an ultrasonic holographic lens 2. The laser 1 is used to emit a laser beam. The ultrasonic holographic lens 2 includes an optical focusing layer 11, an acoustic confinement layer 12, an optical absorption layer 13, an acoustic matching layer 14, and a mixing acoustic holographic layer 15 arranged in sequence along the optical path direction of the laser beam. The optical absorption layer 13 is used to absorb the optical energy of the laser beam to generate ultrasonic waves. The mixing acoustic holographic layer 15 includes a plurality of holographic units 150 with different thicknesses. By adjusting the thickness of the holographic units 150, the phase and amplitude of the ultrasonic waves are controlled to meet the reconstruction of holographic sound fields with multiple preset frequencies.

[0067] An identification module 3, which is used to identify the holographic sound field and feedback holographic sound field information, is arranged on the identification surface of the holographic sound field.

[0068] A control module 4 is respectively connected to the identification module 3 and the laser 1. After obtaining the holographic sound field information, it is used to control the laser 1 to emit a new continuous modulated laser beam for the ultrasonic holographic lens 2 to reconstruct a new holographic sound field.

[0069] The regulation method is applicable to obtaining holographic sound fields at multiple preset frequencies of a continuous modulated laser beam, including:

[0070] S1: Obtain a continuous modulated laser beam with a prior preset frequency, and generate a light spot after optical focusing by the optical focusing layer 11.

[0071] S2: The optical absorption layer 13 absorbs the optical energy of the light spot to generate at least one ultrasonic wave, and the acoustic confinement layer 12 acoustically confines the ultrasonic wave to form a laser ultrasonic field.

[0072] S3: Use the acoustic matching layer 14 to acoustically match and couple the laser ultrasonic field to the mixing acoustic holographic layer 15 to generate a holographic sound field with a prior preset frequency in the propagation medium.

[0073] Repeat S1 to S3 to sequentially complete obtaining holographic sound fields of the continuous modulated laser beam at its subsequent preset frequencies.

[0074] It should be noted that the optical focusing layer 11 is used to obtain a continuous modulated laser beam with a prior preset frequency and generate a light spot after optical focusing. The optical focusing layer 11 includes an optical focusing lens, and the optical focusing lens can be composed of a single-focus optical focusing lens or a multi-focus optical microlens array, which is used to condense the modulated laser beam to generate at least one ultrasonic wave.

[0075] The material of the acoustic confinement layer 12 is composed of a vitreous rigid material, a thin-film flexible material, a gel, or a solution material with low optical absorption rate, and is used for the forward penetration of the laser beam.

[0076] The light absorption layer 13 is used to absorb the light energy of the light spot, generate at least one ultrasonic wave, and perform acoustic confinement on the ultrasonic wave. The ultrasonic waves are reflected and superimposed in the acoustic confinement layer to form a laser ultrasonic field. The material of the light absorption layer 13 is composed of materials with high optical absorption rates such as metals, carbon, or graphite. In this embodiment, the high optical absorption rate is greater than 0.8, and the low optical absorption rate is less than 0.2.

[0077] The acoustic matching layer 14 is used to perform characteristic matching processing on the laser ultrasonic field. Its material has a relatively high coefficient of thermal expansion. In this embodiment, the coefficient of thermal expansion is 0.92×10 -3 K -1 。

[0078] The mixed-frequency acoustic holographic layer 15 includes a plurality of holographic units 150 and is used to perform holographic processing on the laser ultrasonic field to generate a holographic acoustic field in the propagation medium. Among them, the acoustic impedance of the material of the mixed-frequency acoustic holographic layer 15 is the same as or similar to that of the acoustic matching layer 14.

[0079] Based on the control device of this embodiment, a control method for a laser ultrasonic system is provided, which is applicable to continuously modulating a laser beam to obtain holographic acoustic fields at its multiple preset frequencies. As Figure 3 shown, it includes:

[0080] Step S100: Obtain a continuously modulated laser beam with a frequency of W1, and generate a light spot after optical focusing by the light focusing layer 11;

[0081] Step S200: The light absorption layer 13 absorbs the light energy of the light spot, generates at least one ultrasonic wave, and the acoustic confinement layer 12 performs acoustic confinement on the ultrasonic wave to form a laser ultrasonic field;

[0082] Step S300: Use the acoustic matching layer 14 to acoustically match and couple the laser ultrasonic field to the mixed-frequency acoustic holographic layer 15 to generate a holographic acoustic field with a frequency of W1 in the propagation medium;

[0083] Step S400: Obtain a continuously modulated laser beam with a frequency of W2, and repeat steps S100 to S300 to generate a holographic acoustic field with a frequency of W2 in the propagation medium.

[0084] It should be noted that absorbing the light energy of the light spot, generating at least one ultrasonic wave, and performing acoustic confinement on the ultrasonic wave to form a laser ultrasonic field specifically includes:

[0085] When the number of ultrasonic waves is one, the ultrasonic wave is an ultrasonic spherical wave;

[0086] When the number of ultrasonic waves is greater than one, the multiple ultrasonic waves are superimposed on each other to form an ultrasonic plane wave. The frequency of the ultrasonic plane wave is the preset frequency of the continuously modulated laser beam, and the preset frequency of the continuously modulated laser beam is consistent with the preset frequency of the acoustic holographic layer;

[0087] Perform acoustic confinement on the ultrasonic plane wave to form a laser ultrasonic field.

[0088] It should be noted that the phase of the ultrasonic wave and the thickness of the holographic unit satisfy the following relationship:

[0089] ,

[0090] where, represents the phase of the ultrasonic wave, represents the preset ultrasonic frequency, represents the sound velocity of the propagation medium, represents the sound velocity of the holographic unit, represents the thickness of the holographic unit.

[0091] It should be noted that the amplitude of the ultrasonic wave and the thickness of the holographic unit satisfy the following relationship:

[0092] ,

[0093] where, represents the amplitude of the ultrasonic wave, represents the sound pressure of the ultrasonic spherical wave after acoustic characteristic matching emitted from the acoustic matching layer, represents the thickness of the holographic unit, represents the acoustic impedance of the acoustic matching layer, represents the impedance of the acoustic holographic layer, represents the acoustic impedance of the propagation medium, represents the wave number of the acoustic holographic layer.

[0094] Taking the preset frequencies of the acoustic holographic layer as 200 kHz and 500 kHz as an example, when driving the mixed-frequency ultrasonic holographic lens with a continuously modulated laser beam, a focused ultrasonic field with preset frequencies of 200 kHz and 500 kHz is generated, and the focal projection distances regulated by the two preset frequencies are 25 mm and 15 mm respectively.

[0095] The mixed-frequency ultrasonic holographic lens used in this embodiment ( Figure 2It has a size of 30×60 mm, and all holographic units 150 are evenly divided into left and right preset frequency regions. The size of the holographic unit 150 is 0.5×0.5 mm, and the material is photosensitive resin; the material of the used acoustic confinement layer is 0.5 mm of polydimethylsiloxane (PDMS); the material of the used optical absorption material is 0.3 mm of carbon nanoparticle material; the material of the used acoustic matching layer is 0.2 mm of polydimethylsiloxane (PDMS). The used optical focusing layer is an array of 300×600 hemispherical lenses with a diameter of 0.1 mm.

[0096] The modulation frequency is preset to 200 kHz, a continuous modulation laser beam with a frequency of 200 kHz is obtained, and through the hemispherical lens array of the optical focusing layer, an array of focused light spots is generated and irradiated on the optical absorption material;

[0097] The optical absorption layer absorbs the light energy of the focused light spots by the laser thermoelastic effect, generates an array of ultrasonic spherical waves, and coherently forms an ultrasonic plane wave with a frequency of 200 kHz. After acoustic confinement of the ultrasonic plane wave, an amplified laser ultrasonic field is formed;

[0098] The amplified laser ultrasonic field is acoustically matched and coupled to the ultrasonic holographic lens. By adjusting the thickness of each holographic unit 150 in the ultrasonic holographic lens, the phase and amplitude of the ultrasonic plane wave are regulated, and finally a focused sound field with a preset frequency of 200 kHz is generated in the air, with a focal length of 25 mm, as Figure 4 shown;

[0099] The modulation frequency is preset to 500 kHz, a continuous modulation laser beam with a frequency of 500 kHz is obtained, and the above operations are repeated to obtain a focused sound field with a preset frequency of 500 kHz in the air, with a focal length of 15 mm, as Figure 5 shown.

[0100] According to the regulation method of the laser ultrasonic system of the embodiment of the present invention, by only controlling the preset frequency of the excitation laser, one or more single or multiple focused ultrasonic sound fields with one or more preset frequencies can be time-division realized in various propagation media through the ultrasonic holographic lens. Compared with the existing regulation method with only one center frequency, the focusing focal position and power of the excitation laser in the regulation method of the present invention can be adjusted, having better freedom.

[0101] According to the regulation method of the laser ultrasonic system of the embodiment of the present invention, non-contact laser driving at a long distance can be realized without high-voltage excitation and wired connection of cables. Compared with the traditional ultrasonic field regulation method relying on ultrasonic sensors, the durability, safety, convenience and applicable fields of use are greatly improved.

[0102] Embodiment 2

[0103] This embodiment is a further variation based on Embodiment 1, providing a control device for a laser ultrasonic system. Among them, the control device includes:

[0104] A laser ultrasonic system, including a laser and an ultrasonic holographic lens. The laser is used to emit a laser beam. The ultrasonic holographic lens includes an optical focusing layer 11, an acoustic confinement layer 12, an optical absorption layer 13, an acoustic matching layer 14, and a single-frequency acoustic holographic layer 16 arranged in sequence along the optical path direction of the laser beam. The optical absorption layer 13 is used to absorb the optical energy of the laser beam to generate ultrasonic waves. The single-frequency acoustic holographic layer 16 includes a plurality of holographic units 160 with different thicknesses. By adjusting the thickness of the holographic units 160, the phase and amplitude of the ultrasonic waves are controlled to meet the reconstruction of holographic sound fields with multiple preset frequencies.

[0105] The control method is applicable to obtaining a holographic sound field at a target preset frequency from a pulsed laser beam, including:

[0106] Obtain a pulse-modulated laser beam, which generates a light spot after being optically focused by the optical focusing layer 11.

[0107] The optical absorption layer 13 absorbs the optical energy of the light spot to generate at least one ultrasonic wave, and the acoustic confinement layer 12 acoustically confines the ultrasonic wave to form a laser ultrasonic field.

[0108] The acoustic matching layer 14 is used to acoustically match and couple the laser ultrasonic field to the single-frequency acoustic holographic layer 16 to generate a holographic sound field at the target preset frequency in the propagation medium.

[0109] It should be noted that when the optical absorption layer 13 generates ultrasonic waves,

[0110] Since the ultrasonic field generated by the pulsed laser beam has an infinite bandwidth, if the number of ultrasonic waves is greater than one, multiple ultrasonic waves will overlap with each other to form an ultrasonic plane wave, and the preset frequency (i.e., the central frequency) of the ultrasonic plane wave is consistent with the preset frequency of the acoustic holographic layer.

[0111] Acoustically confine the ultrasonic plane wave to form a laser ultrasonic field.

[0112] It should be noted that the optical focusing layer 11 is used to obtain a pulse-modulated laser beam at a preset frequency, which generates a light spot after being optically focused. The optical focusing layer 11 includes an optical focusing lens, and the optical focusing lens can be composed of a single-focus optical focusing lens or a multi-focus optical microlens array, which is used to condense the modulated laser beam to generate at least one ultrasonic wave.

[0113] It should be noted that absorbing the optical energy of the light spot to generate at least one ultrasonic wave and acoustically confining the ultrasonic wave to form a laser ultrasonic field specifically includes:

[0114] When the number of ultrasonic waves is one, the ultrasonic wave is an ultrasonic spherical wave;

[0115] When the number of ultrasonic waves is greater than one, multiple ultrasonic waves are superimposed on each other to form an ultrasonic plane wave, and the center frequency of the ultrasonic plane wave is consistent with the preset frequency of the acoustic holographic layer;

[0116] Perform acoustic confinement on the ultrasonic plane wave to form a laser ultrasonic field.

[0117] The material of the acoustic confinement layer 12 is composed of a vitreous rigid material, a thin-film flexible material, a gel or a solution material with low optical absorption rate, and is used for the forward penetration of the laser beam;

[0118] The light absorption layer 13 is used to absorb the light energy of the light spot, generate at least one ultrasonic wave, and perform acoustic confinement on the ultrasonic wave. The ultrasonic waves are reflected and superimposed on the acoustic confinement layer to form a laser ultrasonic field. The material of the light absorption layer 13 is composed of materials with high optical absorption rates such as metal, carbon or graphite. In this embodiment, the high optical absorption rate is greater than 0.8, and the low optical absorption rate is less than 0.2.

[0119] The acoustic matching layer 14 is used to perform characteristic matching processing on the laser ultrasonic field, and its material has a relatively high coefficient of thermal expansion. In this embodiment, the coefficient of thermal expansion is 0.92×10 -3 K -1 。

[0120] The single-frequency acoustic holographic layer 16 includes a plurality of holographic units 160, and is used to perform holographic processing on the laser ultrasonic field to generate a holographic sound field in the propagation medium. Among them, the acoustic impedance of the single-frequency acoustic holographic layer 16 is the same as or close to that of the material of the acoustic matching layer 14.

[0121] Based on the regulation device of this embodiment, a regulation method for a laser ultrasonic system is provided, which is applicable to obtaining a holographic sound field at a target preset frequency by a pulsed modulated laser beam, and includes:

[0122] Step S110: Obtain a pulsed modulated laser beam, and generate a light spot after optical focusing by the light focusing layer 11;

[0123] Step S210: The light absorption layer 13 absorbs the light energy of the light spot, generates at least one ultrasonic wave, and performs acoustic confinement on the ultrasonic wave by the acoustic confinement layer 12 to form a laser ultrasonic field;

[0124] Step S310: Use the acoustic matching layer 14 to acoustically match and couple the laser ultrasonic field to the single-frequency acoustic holographic layer 16 to generate a holographic sound field with a preset frequency in the propagation medium.

[0125] It should be noted that the phase of the ultrasonic wave and the thickness of the holographic unit satisfy the following relationship:

[0126] ,

[0127] wherein, represents the phase of the ultrasonic wave, represents the preset ultrasonic frequency, represents the sound velocity of the propagation medium, represents the sound velocity of the holographic unit, represents the thickness of the holographic unit.

[0128] It should be noted that the amplitude of the ultrasonic wave and the thickness of the holographic unit satisfy the following relationship:

[0129] ,

[0130] wherein, represents the amplitude of the ultrasonic wave, represents the sound pressure of the ultrasonic spherical wave that has undergone acoustic characteristic matching and is emitted from the acoustic matching layer, represents the thickness of the holographic unit, represents the acoustic impedance of the acoustic matching layer, represents the impedance of the single-frequency acoustic holographic layer, represents the acoustic impedance of the propagation medium, represents the wave number of the single-frequency acoustic holographic layer.

[0131] For example, first preset the frequency of the single-frequency ultrasonic holographic lens to 5 MHz, and the focal lengths and spacing of the two foci are 9 mm and 5 mm respectively. Drive the single-frequency ultrasonic holographic lens through a pulsed modulated laser beam to simultaneously generate a dual-focus focused ultrasonic field with a preset frequency of 5 MHz.

[0132] Taking the preset frequency of the acoustic holographic layer as 5 MHz as an example, set the focal length to 9 mm, and drive the single-frequency ultrasonic holographic lens through a pulsed modulated laser beam to simultaneously generate a dual-focus focused ultrasonic field with a preset frequency of 5 MHz.

[0133] The single-frequency ultrasonic holographic lens used in this embodiment ( Figure 6 ) has a size of 10×10 mm, the holographic unit has a size of 0.5×0.5 mm, and the material is photosensitive resin; the material of the acoustic confinement layer used is 0.3 mm thick transparent glass; the optical absorption material used is 0.2 mm thick black metal film; the material of the acoustic matching layer used is 0.2 mm thick polydimethylsiloxane (PDMS). The optical focusing layer used is an array of 100×100 hemispherical lenses with a diameter of 0.1 mm.

[0134] Obtain a pulsed modulated laser beam, and through the hemispherical lens array of the optical focusing layer, generate an array of focused light spots to irradiate on the black metal thin film;

[0135] The black metal thin film absorbs the light energy of the focused light spots by the laser ablation effect, generates an array of broadband ultrasonic spherical waves, and coherently forms an ultrasonic plane wave. After acoustic confinement of the ultrasonic plane wave, an amplified laser ultrasonic field is formed;

[0136] Acoustically match and couple the amplified laser ultrasonic field to the single-frequency ultrasonic holographic lens, and regulate the phase and amplitude of the ultrasonic plane wave by adjusting the thickness of the holographic unit in the single-frequency ultrasonic holographic lens. Finally, a focused sound field with a preset frequency (i.e., the central frequency) of 5 MHz is generated in water, the focal length is 9 mm, and the focal point interval is 5 mm, as Figure 7 shown.

[0137] According to the regulation method of the laser ultrasonic system in the embodiment of the present invention, only by controlling the pulsed laser, it is possible to simultaneously realize single or multiple focused ultrasonic sound fields with a single preset frequency in various propagation media through the single-frequency ultrasonic holographic lens. Compared with the existing regulation method with only one central frequency, the ultrasonic focusing focal position and power in the regulation method of the present invention can be adjusted, having better freedom.

[0138] According to the regulation method of the laser ultrasonic system in the embodiment of the present invention, non-contact laser driving at a long distance can be realized without high-voltage excitation and wired connection of cables. Compared with the traditional ultrasonic field regulation method relying on ultrasonic sensors, the durability, safety, convenience and application fields of use are greatly improved.

[0139] Embodiment 3

[0140] A laser ultrasonic medical device in this embodiment includes the regulation device of the above-mentioned laser ultrasonic system. Among them, the laser ultrasonic medical device can be used for ultrasonic manipulation and driving, ultrasonic detection and imaging, low-power ultrasonic stimulation, power ultrasonic treatment, etc.

[0141] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the invention.

[0142] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the illustrative representations of the above terms do not necessarily refer to the same embodiment or example.

[0143] Obviously, the described embodiments are only a part of the embodiments of this application, rather than all of them. The mention of "embodiment" in this context means that the specific features, structures, or characteristics described in connection with the embodiment can be included in at least one embodiment of this application. The appearance of this phrase at various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. Those skilled in the art can explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts belong to the scope of protection of this application.

[0144] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and purposes of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for controlling a laser ultrasonic system, characterized in that: The laser ultrasonic system comprises: A laser for emitting a laser beam; An ultrasonic holographic lens, the ultrasonic holographic lens comprising a light focusing layer, an acoustic confinement layer, a light absorption layer, an acoustic matching layer and an acoustic holographic layer arranged in sequence along the laser light path direction, wherein the light absorption layer is used to absorb the light energy of the laser beam to generate ultrasonic waves; the acoustic holographic layer comprises a plurality of holographic units of different thicknesses, and the phase and amplitude of the ultrasonic waves are manipulated by adjusting the thickness of the holographic unit to meet the requirements of reconstructing a holographic sound field of a plurality of preset frequencies, wherein the phase of the ultrasonic wave and the thickness of the holographic unit satisfy the following relationship: ， in, represents the phase of the ultrasonic wave, Indicates the preset ultrasonic frequency, is the speed of sound in the propagation medium, represents the speed of sound of the holographic unit, Indicates the thickness of the holographic unit; The control method is suitable for continuously modulating a laser beam to obtain a holographic sound field at multiple preset frequencies, and includes: S1, obtaining a continuously modulated laser beam of a preset frequency, and generating a light spot after optical focusing by the light focusing layer; S2, the light absorption layer absorbs the light energy of the light spot to generate at least one ultrasonic wave, and the ultrasonic wave is acoustically constrained by the acoustic confinement layer to form a laser ultrasonic field; S3, using an acoustic matching layer to acoustically match and couple the laser ultrasonic field to the acoustic holographic layer, so as to generate a holographic acoustic field of a preset frequency in a propagation medium; Repeat S1 to S3 to sequentially complete the continuous modulation of the laser beam to obtain the holographic sound field at the preset frequency.

2. A control method for a laser ultrasonic system, characterized in that: The laser ultrasonic system comprises: A laser for emitting a laser beam; An ultrasonic holographic lens, the ultrasonic holographic lens comprising a light focusing layer, an acoustic confinement layer, a light absorption layer, an acoustic matching layer and an acoustic holographic layer arranged in sequence along the laser light path direction, wherein the light absorption layer is used to absorb the light energy of the laser beam to generate ultrasonic waves; the acoustic holographic layer comprises a plurality of holographic units of different thicknesses, and the phase and amplitude of the ultrasonic waves are manipulated by adjusting the thickness of the holographic unit to meet the requirements of reconstructing a holographic sound field of a preset target frequency, wherein the phase of the ultrasonic wave and the thickness of the holographic unit satisfy the following relationship: ， in, represents the phase of the ultrasonic wave, Indicates the preset ultrasonic frequency, is the speed of sound in the propagation medium, represents the speed of sound of the holographic unit, Indicates the thickness of the holographic unit; The control method is applicable to a pulsed laser beam to obtain a holographic sound field at a target preset frequency, and includes: Acquire a pulsed laser beam, and generate a light spot after optically focusing through the light focusing layer; The light absorption layer absorbs the light energy of the light spot to generate at least one ultrasonic wave, and the ultrasonic wave is acoustically constrained by the acoustic confinement layer to form a laser ultrasonic field; The laser ultrasonic field is acoustically matched and coupled to the acoustic holographic layer by using an acoustic matching layer, so as to generate a holographic acoustic field of a target preset frequency in a propagation medium.

3. The control method of the laser ultrasonic system according to claim 1 or 2, characterized in that: When the light absorbing layer generates ultrasonic waves, If the number of ultrasonic waves is greater than one, the plurality of ultrasonic waves will be superimposed on each other to form an ultrasonic plane wave, the frequency of which is consistent with the preset frequency of the acoustic holographic layer; The ultrasonic plane wave is acoustically confined to form a laser ultrasonic field.

4. The control method of the laser ultrasonic system according to claim 1 or 2, characterized in that: The light focusing layer comprises an optical focusing lens, wherein the optical focusing lens is one or more hemispherical lenses, which are used to focus the laser beam to generate at least one ultrasonic wave.

5. The control method of the laser ultrasonic system according to claim 1 or 2, characterized in that: The amplitude of the ultrasonic wave and the thickness of the holographic unit satisfy the following relationship: ， in, represents the amplitude of ultrasonic wave, It represents the sound pressure of the ultrasonic spherical wave emitted by the acoustic matching layer after the acoustic characteristics are matched. represents the thickness of the holographic unit, represents the acoustic impedance of the acoustic matching layer, represents the impedance of the acoustic holographic layer, represents the acoustic impedance of the propagation medium, Represents the wave number of the acoustic holographic layer.

6. A control device for a laser ultrasonic system, characterized in that: A method for controlling a laser ultrasonic system according to claim 1 or 2, comprising: A laser ultrasonic system, comprising a laser and an ultrasonic holographic lens, for obtaining a holographic sound field by transmitting a laser beam emitted by the laser through the ultrasonic holographic lens; The recognition module is used to recognize the holographic sound field and feedback the holographic sound field information, and is arranged on the recognition surface of the holographic sound field; The control module is connected to the recognition module and the laser respectively, and is used to control the laser to emit a new laser beam after acquiring the holographic sound field information, so as to reconstruct a new holographic sound field by the ultrasonic holographic lens.

7. The control device of the laser ultrasonic system according to claim 6, characterized in that: The ultrasonic holographic lens comprises: The light focusing layer is used to obtain a previously preset laser beam and generate a light spot after optical focusing; An acoustic confinement layer for forward penetration of the laser beam; A light absorbing layer, used for absorbing the light energy of the light spot and generating at least one ultrasonic wave, the ultrasonic wave is acoustically constrained, and is reflected and superimposed on the acoustic constraining layer to form a laser ultrasonic field; An acoustic matching layer, used for performing feature matching processing on the laser ultrasonic field; The acoustic holographic layer is used to perform holographic processing on the laser ultrasonic field to generate a holographic acoustic field in a propagation medium.

8. A laser ultrasonic medical device, comprising the control device of the laser ultrasonic system according to claim 7, characterized in that: The laser ultrasound medical device can be used for ultrasound manipulation and driving, ultrasound detection imaging, low-power ultrasound stimulation and power ultrasound treatment.

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